Ethylene-propylene-diene terpolymer (EPDM) is extensively used in a variety of applications. For example, it is particularly useful as a polymeric sheeting material that, because of its physical properties, flexibility, weathering resistance, low temperature properties and heat aging resistance, has gained acceptance as a roofing membrane for covering industrial and commercial roofs. These rubber roofing membranes are typically applied to the roof surface in a vulcanized or cured state and serve as an effective barrier to prevent the penetration of moisture to the covered roof.
These roofing membranes are typically prepared by compounding the base polymer of EPDM with appropriate fillers, processing oils, and other desired ingredients such as plasticizers, antidegradants, adhesive-enhancing promoters, etc., in a suitable mixer, and calendering the resulting compound into the desired thickness. The roofing membrane may also be cured by vulcanizing the resultant sheet in the presence of one or more vulcanizing agents and/or compatible vulcanizing accelerators.
Mineral fillers such as clay, talc, silicas, mica, calcium carbonate, and the like are typically added to a roofing membrane formulation to increase burn resistivity, such as described in U.S. Pat. No. 5,468,550.
Roofing membranes typically also include flame retardants (FR). Decabromodiphenyl oxide (DBDPO) is a well-known halogen-containing FR used in EPDM roofing membranes. However, DBDPO has become an environmental concern due to its high bromine content (83 wt %). Due to these concerns, and also to address regulatory changes in the industry, there exists a need for DBDPO-free polymeric compositions, which also provide flame retardant properties.
There is an ongoing desire to find materials that are useful as flame retardants within rubber roofing membranes and that do not have a deleterious impact on the rubber roofing membranes.